Many systems, such as navigation and control systems, have a need to determine if a signal input is faulty. Consequently, many different techniques have been developed to detect a faulty signal. For example, some systems use a mid-value select technique. The mid-value select technique attempts to select a value from a plurality of inputs which meets a pre-defined definition for a mid-value of the plurality of inputs. Most mid-value select techniques assume that the redundant signals used match exactly if non-faulty. However, given slight variations in circuit elements and signal path, noise can be inserted into individual signals. Due to the slight variation, non-faulty redundant signals cannot be guaranteed to match exactly. Thus, mid-value select techniques have some limitations in detecting faults.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a fault detection system which accounts for variations in the sensor signals.